[molpro-user] GPGPU calculation for Molpro?
Gerald Knizia
knizia at theochem.uni-stuttgart.de
Tue Jun 30 22:46:29 BST 2009
On Monday 29 June 2009 12:13, Gang wrote:
> It is about the GPGPU calculation. People claim that this graphic
> processor associated calculation could increase the speed of some
> programs by a factor of 5 - 100, which is quite impressive. And PGI just
> released a new compiler base on this new technology.
There certainly is substantial potential in GPGPU application. However, the
area with the greatest benefits are clearly single precision calculations
which involve very large matrices (or other massive amounts of data with few
interdependencies manipulated in exactly the same way for all the data).
Some hardware developers I spoke to assured me that it will stay like this for
quite some time. Mainly because some double precision arithmetic units
require 4 times as much chip space as single precision units, and for the
main application area of the cards---computer graphics--single precision is
perfectly sufficient.
> The GPGPU calculation seems quite good at matrix operation and
> image processing.
> Which kind of operations are molpro doing? Will GPGPU calculation
> increase the speed of molpro quite a lot?
Molpro is doing lots of matrix operations, but most of them involve matrices
which are too small for an efficient use of GPUs. A straightforward exchange
of a normal BLAS with a GPU based BLAS, for example, has been tried, but
currently does not offer substantial increases in computation time relative
to a Multi-Core BLAS or pure parallel execution on the CPU.
This may change in the future when the software can be adapted to the new
hardware developments. But this is a very complex and complicated endeavor
and will require some time.
--
Gerald Knizia
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